1. Field of the Invention
The present invention relates to a temperature measuring device for measuring a temperature of a living body, in particular, a temperature measuring device capable of achieving continuous measurement of a temperature with ease.
2. Description of the Related Art
Up to now, in a hospital and the like, body temperatures of patients are measured and managed on a regular basis. In general, to measure the body temperature, a clinical thermometer is attached to a body part to be measured of a subject and held still for a predetermined time until the measurement is completed. Further, it is important to measure a deep body temperature in body temperature management, monitoring of a bloodstream state, and the like during a surgical operation. However, it is difficult to measure the deep body temperature in a normal state. In general, in order to measure the body temperature, a surface temperature of a living body, which is different from a deep body temperature thereof in an ordinary state, is measured, and hence in a case where the measurement is performed with the clinical thermometer held under the armpit, it is necessary to wait until the deep body temperature and the surface temperature reach equilibrium with the armpit closed. Further, a clinical thermometer is commercially available which predicts an equilibrium point by substituting a state of change in temperature until the deep body temperature and the surface temperature reach equilibrium into a formula and determines the equilibrium point as the body temperature. Further, after completing the measurement, a measurer needs to perform such work of confirming and recording a result of the measurement.
However, in a case where the subject is an infant or a seriously ill patient, it is difficult to keep the clinical thermometer attached to the body part to be measured, and it is not easy to perform accurate body temperature measurement. Further, a prediction type clinical thermometer may often produce a measurement result having a large error because the change in temperature from the start of the measurement becomes unstable in a case where the attachment is not stable or in a case where an environment has changed. Further, the work of confirming and recording the result of the measurement imposes a heavy load on the measurer, and it is desired that the recording be performed without bothering the measurer.
Against such a backdrop, for example, JP 09-126905 A discloses, in page 2 and FIG. 1, a body temperature pickup including a temperature sensing element that is brought into direct contact with the body of the subject and a body temperature measuring unit connected to the temperature sensing element via a lead wire. The body temperature pickup (clinical thermometer) disclosed in JP 09-126905 A includes the disc-like temperature sensing element having a self-adhesive pad and the body temperature measuring unit connected to the temperature sensing element via the lead wire. The temperature sensing element is connected to the body temperature measuring unit via the lead wire at all times, and a temperature (body temperature) detected by the temperature sensing element is measured. It is disclosed that this clinical thermometer allows the self-adhesive pad to be adhered on the body of the subject with ease, thereby being suitable for the measurement of the body temperature of the patient whose body is hard to stabilize.
Further, for example, JP 2010-197244 A discloses, in page 4 and FIG. 1, a body temperature measuring system including: a clinical thermometer having a wireless tag (wireless communication means) including a semiconductor body temperature sensor; and a portable data reader. Hereinafter, referring to FIG. 10, description is made of an outline of the conventional body temperature measuring system disclosed in JP 2010-197244 A. In FIG. 10, the conventional body temperature measuring system includes: a clinical thermometer (adhesive-type clinical thermometer including an antenna) 100 in which the wireless tag including the temperature sensor is located; and a data reader 110 that is portable for the measurer.
The clinical thermometer 100 has a body temperature tag 103, which serves as the wireless tag, sandwiched and fixed between a surface film 101 and a back film 102. The body temperature tag 103 is provided with an antenna unit 104 and a processing unit 105 including the temperature sensor.
Here, the body temperature tag 103 has power supplied to the processing unit 105 by receiving power supply from the data reader 110 via the antenna unit 104 (power supply by generation of an induced electromotive force caused by an electromagnetic wave; arrow A), and transmits temperature information measured by the temperature sensor to the data reader 110 via the antenna unit 104 (arrow B). This indicates that the body temperature tag 103 operates by receiving the power supply from the data reader 110 and hence does not need to have a power source built therein, which can achieve a smaller size and lighter weight.
Further, for example, JP 2002-372464 A discloses, in page 8 and FIG. 18, an electronic clinical thermometer that can estimate a deep body temperature by directly measuring a surface temperature of the living body in real time and calculating the deep body temperature based on a result thereof according to a heat conduction equation. Hereinafter, referring to FIGS. 24A and 24B, description is made of an outline of the conventional electronic clinical thermometer disclosed in JP 2002-372464 A.
FIG. 24A is a sectional view illustrating an internal structure of a probe of the conventional electronic clinical thermometer, in which a top surface and a side surface of a probe 300 are covered with a cover 301 formed of a metallic material or the like, and heat insulating materials 302a and 302b different in thermal conductivity are located adjacent to each other in a longitudinal direction below a cover top surface portion 301a. Further, temperature sensors 303a and 303b are located in contact with under surfaces of the heat insulating materials 302a and 302b, respectively. FIG. 24B illustrates a structure of the probe 300 viewed from the side of the cover top surface portion 301a. The temperature sensors 303a and 303b are each located in a center part of each of the heat insulating materials 302a and 302b having a substantially cuboid shape.
It is disclosed that in the measurement using the above-mentioned electronic clinical thermometer, by bringing the cover top surface portion 301a of the probe 300 into contact with a living body 310, a temperature and a change over time thereof of potions are measured, which are brought into contact with a living body surface via the heat insulating materials 302a and 302b different in thermal conductivity. Then, a known heat conduction equation is solved based on obtained temperature data, thereby allowing estimation of the deep temperature inside the living body.
Further, as another conventional technology, for example, JP 2007-315917 A discloses, in page 6 and FIG. 5, a deep temperature measuring device including a deep temperature probe and a communication display device. Hereinafter, referring to FIG. 25, description is made of an outline of the conventional deep temperature measuring device disclosed in JP 2007-315917 A.
In FIG. 25, IC tags 402 and 403 with temperature sensors are located inside a metallic material portion 401 of a deep temperature probe 400. Therefore, temperatures detected by the IC tags 402 and 403 with temperature sensors correspond to the temperature of the metallic material portion 401 (substantially the same as the outside air temperature). Further, a rigid foamed material 411 that is a heat insulating material is located as a layer below the metallic material portion 401, and IC tags 412 and 413 with temperature sensors are located inside the rigid foamed material 411. The rigid foamed material 411 is segmented into an area R1 having a height h1 and an area R2 having a height h2.
An electromagnetic wave coupling layer 404 and a wiring substrate 405 are located around the metallic material portion 401. The wiring substrate 405 is connected to a wiring from the respective IC tags with temperature sensors and allows communication with an external device. Further, an interval between the IC tags with temperature sensors that are located so as to be opposed to each other across the rigid foamed material 411 in a vertical direction is defined as follows. Assuming that the interval between the IC tags 402 and 412 with temperature sensors is set as d1 and the interval between the IC tags 403 and 413 with temperature sensors is set as d2, a relationship of d1>d2 is established between d1 and d2.
It is disclosed that under this condition, the IC tags 412 and 413 of the deep temperature probe 400 are brought into contact with a living body 420, temperatures at respective measurement points are measured by the respective IC tags with temperature sensors, and the deep body temperature is obtained by a calculation using a finite element method in two dimensions (cross-section). Further, the deep temperature probe 400 has a function of transmitting the result of the measurement to an external communication device in a wireless manner.
However, the clinical thermometer of JP 09-126905 A has a problem in that the lead wire connected to the temperature sensing element becomes a heat flow path and the temperature of the temperature sensing element itself is dissipated to the body temperature measuring unit via the lead wire to thereby make it difficult to measure a body temperature with accuracy.
Further, the body temperature measuring system of JP 2010-197244 A has a problem of a large restriction on the use in that an operable distance between the wireless tag and the data reader being short (on the order of 5 mm to 15 mm) inhibits the communication between the wireless tag and the data reader that are far apart from each other in a case where the subject having the wireless tag attached to the surface of his/her body wears thick clothes, a case where the subject is asleep with a blanket or a comforter, and other such cases. Further, if the output power of the wireless communication is raised in order to widen the operable distance, there arises a problem of an increase in power consumption and a crosstalk caused with respect to another wireless tag.
Further, in the probe of the conventional electronic clinical thermometer of JP 2002-372464 A, as illustrated in FIGS. 24A and 24B, the cover 301 made of metal, the heat insulating materials 302a and 302b different in thermal conductivity, and the temperature sensors 303a and 303b are integrally formed by being stacked one on another, and hence an outer shape of the probe is large and thick. It is not preferred that the probe be continuously attached to the body of the subject for the purpose of the continuous measurement of the body temperature because a large load is imposed on the subject. Further, the probe and a main body cost high because all functional parts are integrally formed, and hence disposal thereof after one use by being attached to the subject for the purpose of infection prevention or the like leads to a problem of excessive cost.
Further, in the deep temperature probe of the deep temperature measuring device of JP 2007-315917 A, as illustrated in FIG. 25, the metallic material portion 401 and the rigid foamed material 411 being the heat insulating material having different thicknesses are stacked one on the other, each of which is integrally formed with a plurality of IC tags, and hence the outer shape of the deep temperature probe is large and thick, which makes it difficult to continuously attach the probe to the subject. Further, the probe costs high because all functional parts including the IC tags are integrally formed, and hence disposal thereof after one use by being attached to the subject for the purpose of infection prevention or the like leads to a problem of excessive cost.
Further, in recent years, in order to continuously observe the patient's condition and immediately handle an abrupt change in the condition, there is a demand for the body temperature measurement that enables the body temperature of the patient to be continuously measured twenty-four hours a day and progress of the body temperature to be continuously grasped and stored. However, with the clinical thermometers of JP 09-126905 A and JP 2002-372464 A, even if the temperature sensing element can be continuously attached to the patient, the reading and recording of the body temperature need to be performed by the measurer beside the patient at every time in the same manner as in the conventional technology, thereby making it extremely difficult to correspond to the continuous measurement of the body temperature twenty-four hours a day.
Further, in the same manner, in the body temperature measuring system of JP 2010-197244 A, even if the wireless tag is continuously attached to the body of the subject, the actual body temperature measurement makes it necessary for the measurer to bring the data reader into close proximity to the wireless tag and perform a measurement operation, thereby making it extremely difficult to continuously measure the body temperature of the subject twenty-four hours a day.
Further, in the same manner, in the deep temperature measuring device of JP 2007-315917 A, the deep temperature probe needs to be manufactured into a considerably small size in order to be continuously attached to the subject. However, even if the probe can be manufactured into a small size, it is assumed that a wireless communication distance from the external communication device becomes extremely short due to a restriction on an antenna or a restriction on battery capacity, and the actual body temperature measurement makes it necessary for the measurer to bring a communication device into close proximity to the deep temperature probe and perform the measurement operation. Therefore, it is practically difficult to continuously measure the body temperature of the subject twenty-four hours a day.